Several children, pretending they are playing in the jungle, suspend a rope from an overhead tree limb. A child of mass 40 kg running at 8.0m/s grabs the rope and swings off the level ground.(adsbygoogle = window.adsbygoogle || []).push({});

a) What maximum height does the child reach?

b) How fast would a 30 kg child have to run to reach the same height as the 40 kg child?

½mv1²+mgh1 = ½mv2²+mgh2

a) m=40kg, v1=8.0m/s, h1=0m, g=9.8m/s², v2=0m/s (at max height v=0)

h2=?

½mv1²+mgh1 = ½mv2²+mgh2

½mv1²= mgh2

h2 = 3.27m = 3m (is this correct?)

im really confused with B... coz i got 8m/s... it doesn't make sense to me how they can run at the same speed and achieve the same height??!!

this is really urgent... so please help me!! >_< thanks!

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# Homework Help: Mechanical Energy

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